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Post by philip42h on Apr 22, 2020 12:55:34 GMT

OK, since during lock-down our cars probably aren't going far enough to recharge the battery after starting the engine, I thought it might not be a bad idea to invest in a new-fangled smart battery charger and put both cars on charge once a week or so.

With the RAV this is really straightforward ... connect up the charger, preferably the right way round, select 12V battery and an hour or so later I have a reassuring green light telling me that "bulk charge is complete; optimising battery for extended life" - it did start off showing less that 25% charge! So far so good ...

The wife's V40 XC has a stop-start system. Being a Volvo it obviously has to have two batteries - a big one (the starter battery) that you can see and a not so big one (the support battery) hidden away low down underneath. And the support battery is, of course, an Absorbed Glass Mat (AGM) battery - and you can't / mustn't use a standard charger on an AGM battery. I knew none of this 24 hrs ago!

So that's my question / confusion really - what is it about AGM batteries that requires a special charging mode? My understanding, so far, is that they can't stand being charged too quickly ... So can I select AGM mode 'permanently' and use it for both the standard and AGM batteries - albeit that it might not charge a standard battery quite so quickly?

Post by philip42h on Apr 22, 2020 14:26:08 GMT

What type of battery is the big starter one Philip? Are you sure that's not AGM too?

That's a very good point ... my reading of the destructions seemed to suggest that that just the support battery was AGM but I've done the obvious thing and gone out to look! The starter battery is almost entire shrouded in 'stuff' and the only three letters I can see read AGM! So I am now quite sure that both batteries are the AGM type which confirms the mode setting I need on the charger for the Volvo ...

Post by philip42h on Apr 22, 2020 14:39:00 GMT

OK, continuing RTFM for the Volvo it says: "The negative battery terminal on the car's main battery must never be used for connecting an external battery or battery charger - only the car chassis may be used as the grounding point. If this instruction is not observed then the Start/Stop function may temporarily cease to work."

What's that all about? Isn't the negative battery terminal grounded to the chassis any way?

Post by davrav on Apr 22, 2020 14:45:55 GMT

OK, continuing RTFM for the Volvo it says: "The negative battery terminal on the car's main battery must never be used for connecting an external battery or battery charger - only the car chassis may be used as the grounding point. If this instruction is not observed then the Start/Stop function may temporarily cease to work."

What's that all about? Isn't the negative battery terminal grounded to the chassis any way?

Who cares ... I'll just follow orders ... but ... ?

I'm guessing that there is a control gizmo [technical term there Kev] of some sort attached to the battery -ve that could potentially be damaged. On the SLK I have there is a separate grounding point and +ve terminal for jump starting. I, and many others, use those for trickle charging as they are conveniently located. Where is the recommended connection point for jump starting the VOLVO?

Post by philip42h on Apr 22, 2020 15:02:28 GMT

OK, continuing RTFM for the Volvo it says: "The negative battery terminal on the car's main battery must never be used for connecting an external battery or battery charger - only the car chassis may be used as the grounding point. If this instruction is not observed then the Start/Stop function may temporarily cease to work."

What's that all about? Isn't the negative battery terminal grounded to the chassis any way?

Who cares ... I'll just follow orders ... but ... ?

I'm guessing that there is a control gizmo [technical term there Kev] of some sort attached to the battery -ve that could potentially be damaged. On the SLK I have there is a separate grounding point and +ve terminal for jump starting. I, and many others, use those for trickle charging as they are conveniently located. Where is the recommended connection point for jump starting the VOLVO?

I don't think there is one (as in recommended). For jump starting they say: "Connect the other clamp to a grounding point, e.g. right-hand engine mounting at the top, the outer screw head". But that's on the other side of the engine to the battery - it would be no problem using jump leads but there no way the charger leads will stretch that far! There's a convenient something electrical bolted onto the chassis just adjacent to the battery and I am using that as we 'speak' ...

Post by firemac on Apr 22, 2020 15:46:26 GMT

I still have an Optimate that I can press into service if necessary but so far our essential shopping trips etc seem to keep the battery on the RAV healthy. However the Optimate was always used on my bikes and it came with a little adaptor cable that could be fitted permanently to the battery terminals; the other end of the adaptor cable was fitted with a socket that fits the one on the end of the charger's cable. It meant that connecting to the battery was a simple matter of clipping the connectors together and not having to worry about using crocodile clips on odd bolt heads.If your unit did not come with such an adaptor, it should be possible to get one (or two for the second car) from the manufacturer's website.Also some of the smart chargers come with fittings that allow the use of the cigar lighter for connecting the unit?

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Post by bigkev on Apr 22, 2020 15:56:27 GMT

OK, continuing RTFM for the Volvo it says: "The negative battery terminal on the car's main battery must never be used for connecting an external battery or battery charger - only the car chassis may be used as the grounding point. If this instruction is not observed then the Start/Stop function may temporarily cease to work."

What's that all about? Isn't the negative battery terminal grounded to the chassis any way?

Who cares ... I'll just follow orders ... but ... ?

The Jag manual and/or Forum advises against connection of chargers and jump leads to negative post due to gas/explosion risk from sparking......more relevant to Jag maybe as batteries are in enclosed area of boot under floor. I have the wee “comfort connector” Jim refers to above, incorporating a red, amber, and green led battery condition indicator......utter posh/pish.

Post by davrav on Apr 22, 2020 16:16:16 GMT

So, I queried CTEK with regard to the CTEK MXS 5.0 and if it could automatically detect regular V AGM batteries and this is their reply:Dear Sir,

Thank you for your query.

No, charger does not choose for you, you still have to press the button and decide which program you want to use.

Recommendations regarding charging voltage vary a bit.There are many different battery manufacturers and battery models on the market.Please check with the battery manufacturer to get the correct information for your particular battery, as CTEK does not have the particular recommendations for each and every battery brand and model.

All EFB and most AGM- batteries are recommended to charge with normal 14.4V voltage.Some AGM- batteries can be charged with 14.7V for most effective charge.

If no information is possible to acquire, use normal charging option, 14.4V That setting will not harm any battery.

It suits very well most lead/acid batteries, including GEL, EFB, AGM, etc.It is better to charge with a bit too low voltage than too high.